Circuit flutter preventing switch construction



March 30, 1965 R. J. WODTKE 3,176,109

CIRCUIT FLUTTER PREVENTING SWITCH CONSTRUCTION Filed May 2, 1965 2 Sheets-Sheet 1 INVENTOR. ROBERT J. WODTKE HIS ATTORNEYS March 30, 1965 R. J. WODTKE 3,176,109

CIRCUIT FLUTTER PREVENTING SWITCH CONSTRUCTION Filed May 2, 1963 2 sheets-sheet 2 FIG-8 A ,JZO

f E L 22 FIG-9 FIG-IO 7 64 7O Z\ I2O 34 .r -2:, 38A 4 I20 38 70 FIG-l3 INVENTOR. ROBERT J. WODTKE HIS ATTORNEYS United States Patent 3,176,109 CIRCUET FEUTTER FREVENTING SWITCH CUNSTRUETION Robert I. Wodtke, Columbus, Ghio, assiguor to Robertshaw Controls Company, a corporation of Delaware Filed May 2, 1963, Ser. No. 277,509 Claims. (Cl. 200-166) This invention relates to a switch that is capable of making and breaking electrical circuits which are used in modern computers, modern typewriter constructions which simultaneously transmit the message being typed over circuits to distant places, and the switch is also applicable to other similar constructions.

In modern computer circuits, in electric typewriter constrnctions, and in similar constructions above described, any slight flutter or bounce between the contacts of a switch in the circuit will cause such circuit to transmit false signals or impulses. For example, a slight tap of a pencil and any similar slight shock that might be produiced in the construction will cause such a flutter or bounce in the switch contacts that will cause the circuits to transmit false signals. These false signals naturally will produce erroneous computations and erroneous messages, or garbled messages, in such a manner as to render such computer, typewriter, and the like unsatisfactory. The switch of this invention is capable of making and breaking such circuits at proper times without being sensitive to such slight pencil taps, and similar slight shocks.

The circuits which are used in these constructions carry relatively low voltage and ampere loads for transmitting the signals and the like to very sensitive receivers. Any minutely slight disturbances or vibrations between the contacts of a switch in such a circuit will transmit erroneous signals of the controlled circuits. However, the switch or" this construction will transmit proper signals without any such variations or vibrations between the contacts of the switch.

According to this invention, the electrical flow of current between the contacts is maintained constant from the instant of the desired closing of the circuit to the instant of the desired opening of the circuit without any perceptible flutter or break in the circuit. A switch of this invention is capable of preventing any flutter that is longer than 50 millionths of a second (50 microseconds).

This total bounce time of 50 millionths of a second, of this invention, compares with a total bounce time at the closing of a circuit by a standard previous switch during which there is perceptible flutter or break of the circuit in the order of 3 thousandths of a second (3 milliseconds) Also, in a standard previous snap switch the time required for the movable switch contact to remain out of contact from one position to the other, including bounce at the end of the snap, has been in the order of 6 thousandths of a second (6 milliseconds). In a switch embodying this invention such an interval has been in the order of 2 /2 thousandths seconds (2%. milliseconds).

Accordingly, it is an object of this invention to provide a switch capable of preventing flutters and bounces while making and breaking circuits of the character above described.

Other objects of this invention are apparent from this description, the appended claimed subject matter, and the accompanying drawings in which:

FIGURE 1 is a plan view, looking upward in FIGURE 2, of a switch embodying this invention, with the cover removed.

3,176,109 Patented Mar. 33, 1965 FIGURE 2 is a cross section taken along the line 2-2 of FIGUREJ.

FIGURE 3 is a view in perspective view of a portion of the switch shown in FIGURES 1 and 2 with the switch contacts in closed position.

FIGURE 4 is an enlarged cross section along line -tt of FIGURE 1 with the contacts in closed position.

FIGURE 5 shows another embodiment of switch contact providing for a double throw switch construction.

FIGURE 6 shows another embodiment of the switch contact construction in which the fork construction is applied to the movable contact member.

FIGURE 7 is a plan view of the fork prong construction.

FIGURE 8 is a side view of FIGURE 7.

FIGURE 9 is a plan view of a stationary contact member.

FIGURE 10 is a side view of FIGURE 9.

FIGURE 11 is a plan view of the movable contact member.

FIGURE 12 is a side view of FIGURE 11.

FIGURE 13 is a plan view of the cover member as seen from inside the switch casing.

This invention is an improvement over the switches disclosed in the US. patents to T. Y. Korsgren, 2,819,- 362, and E. S. Fergus, 2,897,308. The switch of this invention has been improved over the switches disclosed in these patents so it is capable of use in low voltage and low ampere signal environments in a manner previously not possible with the switche of the patents.

This invention is particularly applicable to a small type of switch wherein very low voltage conditions and very low ampere signal conditions and very sensitive receivers are used in computer designs and the like. The construction is intended to prevent the switch from being jarred open by any shocks of the usual type that are likely which occur in the neighborhood of a computer, such as a shock produced by the tap of a pencil or the like are likely to transmit a fake signal. The two previous patents show snap switches in which the stationary contact is provided with a single leaf spring construction which is intended to follow the movable contact for a certain distance, as the switch opens, to prevent the circuit from being opened until the switchs main movable contact has been definitely moved away from the stationary contact. If the switch is jarred to open the contacts slightly, or if the movable contact bounces when snapped to closed position, the flexible spring on the stationary contact will follow the movable contact and maintain the circuit in closed condition sutliciently for previous uses. However, these previous switches were not intended for the low voltage and ampere loads and sensitive receivers herein contemplated. These prior switches, when used with a computer or the like, will vibrate away from the stationary contact construction sufiiciently to register impulses which produce a wrong computation of some kind unless the embodiments of this invention are provided to prevent this. The leaf springs of the above two patents provide only one leaf spring for the respective stationary contact which is to act as the follower against the movable contact. However, such a leaf spring may take on a harmonic vibration which is likely to make small breaks or flutters in the circuit which were imperceptible in the uses for which these prior switches were made. However, they produce breaks or flutters, which can be registered by the computer circuits, typewriter circuits, and the like, which have been elsewhere described.

xccording to this invention, for example, a leaf spring fork construction 21 with a plurality of fork-like prongs 22 and 24 is provided, in which the prongs are preferably provided with different shapes, masses, widths, weights,

etc, so that they have different periods or frequencies of vibration. Therefore, if one of the fork prongs is likely to produce harmonic makes and breaks or flutters in the circuit, the other fork prong will maintain a constant unfiuttered circuit. In this manner the fork construction of this invention will prevent the computer, typewriter, and the like, from registering a false computation or impulse.

This spring fork construction 28 may be connected to one of a plurality of relatively movable switch electric conductors, such as switch conductor 34 with the fork prongs 22 and 24 providing the first electrical engagement by another of the relatively movable switch conductors, such as conductor at when the conductors 34 and 68 are relatively moving to closed circuit condition, and providing the last disengagement when the conductors 34 and 6d are relatively moving to open circuit condition. The spring fork prong construction therefore maintains an effective non-fluttering and non-bouncing electrical connection from the very first instant of contact of either of the prongs 22 or 24 with the conductor 60 to the very last instant of disconnection of the last of the prongs 22 or 24 to disconnect from the conductor 60.

While two prongs have been disclosed as one embodiment of this invention, more than two forks or other contacting members may be used, if desired.

This fork prong construction 20 has been found effective in a switch construction such as shown in FIGURES 1-4. In the embodiment shown in FIGURES 1-4, a relatively small box like insulating casing 26 may be rectangular in shape and may have a base 28 and side walls 30, 31, 32 and 33. This casing 26 may be made of electrically insulating plastic material.

These side walls may each have, respectively; outer flanges 30A, 31A, 32A, and 33A, which may extend to and be flush with the outer surface 35 of the cover 37. The side walls may also have counter sunk ledges 34H 31B, 32B and 33B, respectively, against which the cover 37 may rest. The corners 30C, 30D, 36E and 30F may have surfaces flush with the surfaces of flanges 30A, 31A, 32A and 33A.

Stationary contact member 34 and 36 and the relatively thick base 38 of a movable contact member 60 may be forced between formations or ledges 4t), 42, 44, and 45, which may 'be integral with the base 28 of casing 25, and which may extend toward the cover 37 to form grooves which receive and hold such contact members. These ledges 4t), 42, 44 and 45 may have surfaces flushwith the surfaces of flanges 30A, 31A, etc.

One or both members 34 and 36 may have added thereto the fork construction 26, which has the fork-like prongs 22 and 24 heretofore described. These fork constructions may be secured to the contact member which carries them by means of rivets 46 or the like.

The stationary contact members 34 and 36 may each have, respectively, stationary contacts 48 and 56. They may be attached to the members 34 and 36 by any suitable means, such as by upset portions 52 and 54 which extend beyond the openings 56 and 58 in the members 34 and 36.

If desired, the contact surface of the contacts 43 and/or may be fiat, as shown.

The movable member base 33 may have a relatively thin, flexible blade 60 extending therefrom, which may have an opening 62 for receiving the movable contact 64. The contact 64 may have a rounded surface 66 for engagement with the prongs 22 and 24 and, if desired, with the stationary contact 48. The contact 64 may be secured to the contact member at in any well known manner, such as through opening 62, with a suitable riveting or soldering action.

The fork member 20 may be made from spring silver sheet material which may be .004 inch in thickness, with gold plating. The distance A of FIGURES 7 and 8,

for example, may be 95 The distance B may be .125.

The distance C may be .035. The distance D may be .023. The distance E may be .055. The opening 68 may be .062" in diameter, more or less.

The stationary members 34 and 36 may be substantially similar, but mirror images of each other, and in the embodiment shown in FIGURES 1-4 the contact member 36 is not provided with the fork formation 20, and the contact 50 may either he a stop member only, or may be a member which controls a circuit not requiring the use of a member corresponding to member 2 The blade d4 may be relatively thin and spring like and may be provided with a tongue 74} to engage an opening in the end of a 6 spring 72. The other end of the 0 spring '72 may receive a tongue 74 in a suitable opening. The tongue 74 may be a continuation of a bent end 76 of a spring actuating member 78 which has a resilient bent portion 8d. The member 78 may have a reverse bend 82 which is received between the formation 4t) and another formation 84 of the casing. The member 78 may also have a reverse end bend 84 received in a notch 86 in the formation 40. An insulating button 83 is carried by the plunger 99 which passes through an opening in the outer flange 31a. The member '78 may be biased upwardly in FIGURE 1, and the plunger 90 may move it downwardly in FIGURE 1 to cause the blade 60 to move upwardly to close contact 64 on contact 48, and to engage the fork prongs 22 and 24. The plunger 90 may be actuated by any suitable lever construction, now shown, which may be fulcrumed in holes 89 on a pair of cars 91 which may be bent from a central base 93. The base 39 may be secured to side members 31A and 31B by rivets S;

The resilient bent portion may be spring biased toward the C spring end 81 and tends to maintain tight contact with the 6 spring as the C spring rolls or turns about the end of blade 60.

The formation 84' and a similar formation on the other side of casing 26 may have surfaces slightly closer to base 28 than the surfaces of countersunk ledges 30B, 313, etc. These formations 84 and 85 respectively receive the thicker lugs 92 and 94 of cover 37, FIG- URE 13.

The lugs 92 and 94 of cover 37 have openings 96 which are aligned with openings 98 so the cover 37 may be secured to the casing 26 by drive screws 10%) which are driven into the openings 98.

The edges and 97 of cover 37 rest on ledges 31B and 33B of casing 26. Edge 99 of cover 37 rests on ledge 36B of casing 26. Edge ltil of cover 37 rests on ledge 32B of casing 26, which edge 183 rests on ledge 45 of casing 26. The extension MP4 of the cover rests on the outer ends 42' and 44' of the ledges 42 and 44. The edges 107 and 16? of cover 37 rest on ledges 107A and 109A of the casing 26. A post 111 made integral with the base 28 of the casing 26 supports the central part 111A of cover 37 against accidental collapse.

The casing 26 is made so it may be attached to a circuit board, not shown, or the like, without interfering with the removal of the cover 37 from the casing 26.

For example, the corners 30C, 30D, 39E and 30F may be provided with openings 102 through which screws may pass from the casing 26 into the circuit board or the like, to secure the casing 26 to such board. A plurality of switches of this invention may therefore be attached to such board or to various parts of a computer, typewriter, etc, by screws through openings 102 readily to establish the required circuits. The covers 37 may be attached or removed from the casings 26 merely by turning the screws in openings S without molesting the screws in openings N52. The stationary and movable contact members 34, 36 and 33 have extensions 34A, 36A and 38A to which the conductors of the circuits may be attached.

While a desirable casing and cover construction has been disclosed in connection with the contact constructions of this invention, difierent casing and cover constructions or other switch mountings may be used.

FIGURE 5 shows an embodiment in which both of the stationary contact members 34' and 36' may have fork constructions 20 attached thereto. The movable blade 60' and the remainder of the switch structure may be similar to that shown in FIGURES 1-4, or of any other construction, as desired.

FIGURE 6 shows an embodiment in which one or two fork constructions 20 may be attached to the movable member 60". The stationary contact members 34" and 36 are not provided with fork members. The remainder of the switch construction may be similar to that shown in connection with FIGURES 1-4 or of any other construction, as desired.

The stationary contact member 34 (and similar member 36) may be constructed as shown in FIGURES 9 and 10, of relatively thick and stiff metal so it remains substantially stationary when in use. A notch 110 may be provided to engage a ledge 112, FIGURE 2, which may be made in the space between the ledges 40 and 42. This locks the contact member 34 longitudinally in place. The member 34 may also be provided with dimples or the like 114 to insure tight engagement of the member 114 in the space between the ledges 40 and 42.

The material of member 34 (and 36) may be made so it can be given a permanent bend, as indicated by dotted lines 34', FIGURE 10, to position the contact 48 at a slight angle. This is to compensate for the bend in the movable contact member as such movable contact member moves toward the stationary contact, as indicated in FIGURE 12.

The movable contact member may be made to provide a relatively thick base 38 and a thin flexible blade 60 as shown in FIGURES 11 and 12. A metal sheet may be folded to provide the sides 114' and 116 of base 38 on each side of the extension 118 of blade 60. An oblong protrusion or blade 12% previously may have been struck in one of the sides, such as side 114', to bear against formation 42 or 44. A notch 110 may be formed in the sides 114, 116 and extension 118 to receive and lock longitudinally with a ledge 112, FIGURE 2, in the space between ledges 42 and 44.

The blade 60 bends as shown in FIGURE 12, and the stationary member 34 may be permanently bent slightly near its end, as indicated in dotted lines 34, FIGURES and 12, substantially parallel with the bent end of contact blade 66 when contact is made. However, the rounded surface 66 of the contact button 64 will compensate for any reasonable lack of parallelism between the members 34 and 60. The same bent end condition, in mirror image, may be provided for member 36, if desired.

The casing 26 may be made relatively small and the various parts may be of a size more or less in proportion to the size of the casing. For example, in one size of switch that has been found satisfactory, the outer surfaces of sides 30 and 32 may be approximately 1%; inches apart and the outer surfaces of sides 31 and 34 may be inch apart, and the sides 30-34 of the switch may be inch wide, so that the switch is inch thick.

These switches may be attached where desired to establish non-fluttering circuits.

It is thus to be seen that switches made in accordance with this invention may be used to transmit signals and impulses in computers, long distance, typewriters and similar constructions with substantially no flutter or bounce in the current, and may be attached or placed wherever desired.

While the form of the invention now preferred has been disclosed as required by statute, other forms may be used, all coming within the scope of the claimed subject matter which follows.

What is claimed is:

1. In combination: a first contact means with a first contact button; a second contact means with a second contact button, said contact means being relatively movable toward and away from each other for electrical connection between and electrical disconnection from each other; and a flexible conducting member electrically connected with one of said contact means and having two conducting prongs, both prongs being electrically connected to said one of said contact means and extending into the space between said first and second contact means buttons to contact said buttons which prongs produce the first electrical connection between said contact means when said contact means are moving relatively toward each other and produce the last electrical engagement between said contact means when said contact means are moving away from each other.

2. A combination according to claim 1 in which snap acting means produce a snap action between said contact means during relative movement toward and away from each other.

3. A combination according to claim 2 in which said snap acting means include a 6 spring having one end engaging one of said contact means and having its other end moved back and forth by an actuator to produce said snap action.

4. A combination according to claim 3 in which said actuator includes a leaf spring having a bent end having a tongue engagement with said 0 spring.

5. A combination according to claim 2 which is moun ed within a box-like enclosure having enclosure attachment means for attachment to an enclosure support, and a cover member for said enclosure which is attachable to and disconnectable from said box-like enclosure independently of said enclosure attachment means.

6. A combination according to claim 1 in which said prongs have oscillation frequencies which are different in each prong.

7. In combination: a first switch conductor; a second switch conductor, said conductors being relatively movable to closed and open circuit positions to close and open an electric circuit through said conductors; and a flexible conductor fork prong construction electrically connected to one of said conductors and having two flexible conducting prongs, both prongs being electrically connected to said one of said conductors and extending into the space between said conductors, and both prongs being electrically engaged by the other of said conductors when said conductors are being relatively moved to closed circuit position and being disengaged by said other of said conductors when said conductors are being relatively moved to open circuit position.

8. A combination according to claim 7 in which said prongs have oscillation frequencies which are difierent in each prong.

9. A combination according to claim 7 in which said prongs have different masses.

10. A combination according to claim 7 in which said prongs have dilferent widths.

11. A combination according to claim 7 in which said prongs have different shapes.

12. In combination: a first switch conductor having a first contact button; a second switch conductor having a second contact but-ton relatively movable with respect to said first contact button to closed circuit and open circuit positions; and a prong construct-ion having two flexible electrically conductor prongs with both prongs being electrically connected to one of said conductors, both of said prongs being spaced from said buttons when said buttons are in open circuit position and both of said prongs being contacted by said buttons when said buttons are in closed circuit positions.

13. A combination according to claim 12 in which each of said prongs has oscillation frequencies which are different from the oscillation frequencies of the other of said prongs.

14. In combination: a first switch conductor; a second switch conductor, said conductors being relatively movable to closed andopen circuit positions to close and open an electric circuitthrough said conductors; and flexible plural contact constructions electrically connected to one of said conductors which provide the first electrical contact and plural electrically parallelcontacts with the other of said conductors when said conductors are being relatively moved to closed circuit positions and which provide plural electrically parallel contacts and'the last electrical contact with the other of said conductors when said'co-nductors are being relatively moved to open circuit position.

15. A combination according to claim 14 in which some of said contact constructions have oscillation frequencies which are dilferent from the frequencies of the other contact construct-ions.

16. A combination according to claim 14 in which said contact constructions have different masses.

17. A combination. according to claim 14in which said contact constructions have different shapes.

18'. A combination according-to claim 1 in which one of said contact buttons lhas a'flat-surface, and said conducting prongs lie in thesame plane substantially parallel to said flat surfiace.

19. A combination according to claim :1 in which oneof said contact-buttons has a rounded surface and said References Cited in-the file of this patent UNITED STATES PATENTS 1,879,340 Lederer Sept. 27, 1932 Korsgr-en Jan. 7, 1958: 

7. IN COMBINATION: A FIRST SWITCH CONDUCTOR; A SECOND SWITCH CONDUCTOR, SAID CONDUCTORS BEING RELATIVELY MOVABLE TO CLOSED AND OPEN CIRCUIT POSITIONS TO CLOSE AND OPEN AN ELECTRIC CIRCUIT THROUGH SAID CONDUCTORS; AND A FLEXIBLE CONDUCTOR FORK PRONG CONSTRUCTION ELECTRICALLY CONNECTED TO ONE OF SAID CONDUCTORS AND HAVING TWO FLEXIBLE CONDUCTING PRONGS, BOTH PRONGS BEING ELECTRICALLY CONNECTED TO SAID ONE OF SAID CONDUCTORS AND EXTENDING INTO THE SPACE BETWEEN SAID CONDUCTORS, AND BOTH PRONGS BEING ELECTRICALLY ENGAGED BY THE OTHER OF SAID CONDUCTORS WHEN SAID CONDUCTORS ARE BEING RELATIVELY MOVED TO CLOSED CIRCUIT PO- 